The invention relates to stable valepotriate preparations and process for their production.
Valepotriates designate a group of therapeutically valuable substances which may be obtained from the roots and rhizomes of various valerianacea and kentranthus species. The most important representatives of the valepotriates are valtratum, isovaltratum, didrovaltratum and acevaltratum. They may be extracted from the dried drug in amounts of up to approximately 5%. The proportions of the individual valepotriates with respect to each other vary in accordance with the origin of the substance. For example, didrovaltratum predominates in valepotriates of Asian origin and valtratum and isovaltratum predominates in valepotriates of European or Mexican origin. Acevaltratum, on the other hand, is always present in less significant proportions.
Valepotriates are extremely sensitive substances and are rapidly decomposed by the effects of heat, light and chemial agents, and even of moisture though they are practically insoluble in water. Valepotriates cannot be, therefore, maintained in the stable condition under normal storage conditions for an adequate period of time, either in the drug form or in the isolated form.
Because of these difficulties, there have been attempts to prepare valepotriates in a form that would remain stable over a longer period of time.
One such attempt, West German Published application No. 22 30 626, describes a valerian product produced by means of the dissolution of a valerianacea extract in a multivalent alcohol, a fatty oil or an ethereal oil or mixtures thereof. This product purportedly exhibits no appreciable decomposition phenomena after storage for five months at room temperature. In storage at temperatures below 10.degree. C., the solution described is claimed to remain stable for at least 12 months. Without an indication of the details of its effects on the stability, microencapsulation of the above-described solution is also mentioned. The stability of 5 to 12 months observed therein does not represent an adequate period of time for finished medicinal forms. Investigations extending over longer periods of time reveal the onset of decomposition phenomena even in preparations of this type.
A further attempt to stabilize valerian extracts is found in West German Offenlegungsschrift No. 26 54 709 wherein preparations dehydrated to a residual water content of less than 0.5% is described. This proposal requires additional, in part extreme measures, such as for example working under nitrogen. Observations up to about 6 months demonstrate that preparations of this type attain only moderate stability.